the cardiovascular system: blood vessels and circulation

The Cardiovascular System: Blood Vessels and Circulation

The Cardiovascular System: Blood Vessels and Circulation

The Structure of Blood Vessels

Blood Vessel Review•Arteries carry blood away from the heart

• Pulmonary trunk to lungs• Aorta to everything else

•Microcirculation is where exchange occurs• Arterioles to feed the capillaries• Capillaries exchange with the tissues• Venules to receive capillary blood

•Veins bring it back to the heart

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings


A Comparison of a Typical Artery and a Typical Vein

Figure 13-1


Arteries and Veins Have Three Layers•Tunica interna

• Innermost layer (endothelium) in contact with blood

•Tunica media•Middle layer of smooth muscle

•Vasoconstrict or vasodilate

•Tunica externa•Outer layer of loose connective tissue



X Types of Arteries•Elastic arteries

• Largest• Closest to heart• Stretch during systole• Recoil during diastole

•Muscular arteries•Arterioles

• Tiny branches of small arteries• Feeders of capillary networks



X The Structure of the Various Types of Blood Vessels

Figure 13-2


Properties of Capillaries•Where exchange between blood

and cells takes place

•Organized into interconnected capillary beds

•Precapillary sphincters (bands of smooth muscle) controls flow


Figure 13-4(a)

The Organization of a Capillary Bed


The Organization of a Capillary Bed

Figure 13-4(b)


Properties of Veins•Collect blood from capillaries•Merge into medium-sized veins•Merge then into large veins

• Blood pressure is low here• Valves keep blood flowing

toward the heart



The Function of Valves in the Venous System

Figure 13-5

Circulatory Physiology

Factors Affecting Blood Flow•Pressure

• Flow goes up as pressure difference goes up

• Flow goes from higher to lower pressure

• Regulated by nervous and endocrine systems



Factors Affecting Blood Flow•Peripheral resistance

• Flow goes down as resistance goes up



Control of Peripheral Resistance•Consists of three components:

• Vascular resistance•Goes up as diameter is reduced•Arteriole diameter dominates

• Viscosity of blood•Depends on hematocrit

• Turbulence•Cause of pathological sounds



Pressures in the Systemic Circuit•Arterial pressure

• Overcomes peripheral resistance to maintain flow to the organs

•Capillary pressure• Excessive pressure causes edema

•Venous pressure• Low pressure that drives venous return• Affects cardiac output and peripheral flow



Arterial Pressure•Rises during ventricular systole•Falls during ventricular diastole•Pulse pressure is difference between

systolic pressure and diastolic pressure• Lessens with distance from heart


Circulatory PhysiologyPressures Within the Circulatory System

Figure 13-6


Checking the Pulse and Blood Pressure

Figure 13-8(a)

Circulatory PhysiologyChecking the Pulse and Blood Pressure

Figure 13-8(b)


Functions of Capillary Exchange•Maintain communication between

plasma and interstitial fluid•Speed the distribution of nutrients,

hormones, and dissolved gases•Flush antigens to lymphoid tissue•Aid movement of proteins



Dynamics of Capillary Exchange•Small molecules diffuse across

endothelium•Water follows osmotically•Balance of forces determines

direction of filtration• Capillary pressure forces fluid out• Protein osmotic pressure pulls fluid in



Figure 13-7

Forces Acting Across Capillary Walls


Factors Assisting Venous Return•Low venous resistance•Valves in veins•Compression of veins by muscular

contraction•Respiratory pump pulls blood into

thorax



Key Note

Blood flow is the goal. Total peripheral blood flow is equal to cardiac output. Blood pressure is needed to overcome friction to sustain blood flow. If blood pressure is too low, vessels collapse, blood flow stops, and tissues die; if too high, vessel walls stiffen and capillary beds may rupture.


Cardiovascular Regulation

Factors Affecting Tissue Blood Flow•Cardiac output•Peripheral resistance•Blood pressure



Homeostasis of Tissue Perfusion•Autoregulation

• Local control of pre-capillary sphincters

•CNS control• Responds to blood pressure, blood gases

•Hormone control• Short-term adjustments

•Blood pressure•Peripheral resistance

• Long-term adjustments•Blood volume


Cardiovascular RegulationLocal, Neural, and Endocrine Adjustments

That Maintain Blood Pressure and Blood Flow

Figure 13-9


Neural Control of Blood Flow and Pressure•Baroreceptor reflexes

• Adjust cardiac output and peripheral resistance to maintain normal blood pressure

• Driven by baroreceptors•Aortic sinus•Carotid sinus•Atrial baroreceptors



Neural Control of Blood Flow and Pressure•Chemoreceptor reflexes

• Respond to changes in CO2, O2 and pH

• Sense blood and cerebrospinal fluid• Impact cardioacceleratory, cardioinhibitory

and vasomotor centers



Figure 13-101 of 12

Blood pressurereduced

Decreasedcardiacoutput

Vasodilationoccurs

HOMEOSTASISRESTORED

HOMEOSTASISDISTURBED

Blood pressurerises above

normal range

Vasomotorcenters inhibited

Cardioinhibitorycenters stimulated

Cardioacceleratorycenters inhibited

REFLEXRESPONSE

Baroreceptorsstimulated

Inhibition

REFLEXRESPONSE

Baroreceptorsinhibited


Blood pressurefalls below

normal range

HOMEOSTASIS

Normal rangeof bloodpressure

HOMEOSTASISRESTORED

Vasomotorcenters stimulated

Cardioinhibitorycenters inhibited

Cardioacceleratorycenters stimulated

Vasoconstrictionoccurs

Increasedcardiac output

Blood pressureelevated


Figure 13-102 of 12



normal range

HOMEOSTASISNormal range

of bloodpressure


Figure 13-103 of 12



normal range



REFLEXRESPONSE


Inhibition


of bloodpressure


Figure 13-104 of 12




normal range



REFLEXRESPONSE


Inhibition


of bloodpressure


Figure 13-105 of 12


Vasodilationoccurs



normal range




REFLEXRESPONSE


Inhibition


of bloodpressure


Figure 13-106 of 12



Vasodilationoccurs

HOMEOSTASISRESTORED



normal range




REFLEXRESPONSE


Inhibition


of bloodpressure


Figure 13-107 of 12



of bloodpressure


normal range


Figure 13-108 of 12




REFLEXRESPONSE


Inhibition


of bloodpressure


normal range


Figure 13-109 of 12





REFLEXRESPONSE


Inhibition


of bloodpressure


normal range


Figure 13-1010 of 12







REFLEXRESPONSE


Inhibition


of bloodpressure


normal range






HOMEOSTASISRESTORED





REFLEXRESPONSE


Inhibition


of bloodpressure


normal range





Vasodilationoccurs

HOMEOSTASISRESTORED



normal range




REFLEXRESPONSE


Inhibition

REFLEXRESPONSE




normal range

HOMEOSTASIS

Normal rangeof bloodpressure

HOMEOSTASISRESTORED









Decreased pH andO2 levels, elevated CO2

levels in blood and CSF

HOMEOSTASIS

Normal pH, O2,and CO2 levelsin blood and

CSF

REFLEXRESPONSE

Chemoreceptorsstimulated



Vasomotorcenters

stimulated

Increased cardiacoutput and

blood pressure


Increased pH andO2 levels,

decreased CO2

levels in blood

HOMEOSTASISRESTORED

Inhibition

Respiratorycenters

stimulatedRespiratory

rate increases

Figure 13-111 of 6





HOMEOSTASIS


CSFFigure 13-112 of 6





HOMEOSTASIS


CSF

REFLEXRESPONSE




Inhibition

Figure 13-113 of 6





HOMEOSTASIS


CSF

REFLEXRESPONSE




Vasomotorcenters

stimulated


blood pressure


Inhibition

Figure 13-114 of 6





HOMEOSTASIS


CSF

REFLEXRESPONSE




Vasomotorcenters

stimulated


blood pressure


Inhibition

Respiratorycenters


rate increases

Figure 13-115 of 6





HOMEOSTASIS


CSF

REFLEXRESPONSE




Vasomotorcenters

stimulated


blood pressure


Increased pH andO2 levels,

decreased CO2

levels in blood

HOMEOSTASISRESTORED

Inhibition

Respiratorycenters


rate increases

Figure 13-116 of 6


The Hormonal Regulation of Blood Pressure and Blood Volume

Figure 13-12(a)


Figure 13-12(b)

The Hormonal Regulation of Blood Pressure and Blood Volume


X Hormonal CV Regulation•Short-term regulation

• Epinephrine from adrenal medulla• Cardiac output and peripheral

resistance

•Long-term regulation• Antidiuretic Hormone (ADH)• Angiotensin II• Erythropoietin (EPO)• Atrial natriuretic peptide (ANP)



X Hormone Effects on CV Regulation•ADH, angiotensin II promote

vasoconstriction•ADH, aldosterone promote water, salt

retention•EPO stimulates RBC production•ANP promotes sodium, water loss



Key Note

Cardiac output cannot be increased indefinitely, and so blood flow to active tissues must be increased and flow to inactive tissue reduced. A combination of autoregulation, neural regulation, and hormone release accomplish this.


Patterns of CV Response

Exercise and the Cardiovascular System•Cardiac output rises•Blood flow to skeletal muscle increases•Flow to non-essential organs falls•Exercise produces long-term benefits

• Larger stroke volumes• Slower resting heart rates• Greater cardiac reserves


Patterns of CV Response

X Response to Hemorrhage (Blood Loss)• Increase in cardiac output• Mobilization of venous reserves• Peripheral vasoconstriction• Release of hormones that defend

blood volume


The Blood Vessels

Vessels of the Pulmonary Circuit•Pulmonary trunk

• From right ventricle to lungs

•Pulmonary arteries (left and right)

•Pulmonary veins (left and right)

• To left atrium


The Blood Vessels

An Overview of the Pattern of Circulation

Figure 13-13

The Blood Vessels

Figure 13-14

The Pulmonary Circuit

The Blood Vessels

The Systemic Circulation•Ascending aorta

• From left ventricle• Feeds coronary circulation

•Aortic arch• Feeds shoulders, neck, head

•Descending aorta• Feeds inferior body regions


The Blood Vessels

An Overview of the Arterial System

Figure 13-15

The Blood Vessels

Arteries of the Chest and Upper Limb

Figure 13-16

The Blood VesselsA Flow Chart Showing the Arterial Distribution

to the Head, Chest, and Upper Limbs

Figure 13-17

The Blood Vessels

Arteries of the Neck, Head, and Brain

Figure 13-18

The Blood Vessels

Figure 13-19(a)

Major Arteries of the Trunk

The Blood Vessels

Figure 13-19(b)

Major Arteries of the Trunk

The Blood Vessels

X Anatomy of Arterial Supply Contrasts

with Venous Drainage•Major arteries in neck and limbs

all lie deep•Major veins form a dual-venous

drainage• Are either superficial or deep• Serves temperature control needs


The Blood Vessels

Anatomy of Venous Drainage•Superior vena cava

• Drains head, neck, shoulders, arms, chest

• Inferior vena cava• Drains most of body below diaphragm

•Hepatic portal vein• Carries blood draining the digestive system

to the liver for purification and storage of absorbed nutrients


The Blood Vessels

An Overview of the Venous System

Figure 13-20

The Blood VesselsMajor Veins of the Head and Neck

Figure 13-21

The Blood Vessels

The Venous Drainage of the Abdomen and Chest

Figure 13-22

The Blood Vessels

A Flow Chart of the Circulation to the Superior and Inferior Venae Cavae

Figure 13-23(a)

The Blood VesselsA Flow Chart of the Circulation to the Superior and Inferior Venae Cavae

Figure 13-23(b)

The Blood VesselsThe Hepatic Portal System

Figure 13-24

The Blood Vessels

Fetal Circulation•Placenta

• Receives two umbilical arteries from fetus

• Drained by one umbilical vein to the fetus•Joins ductus venosus in liver


The Blood Vessels

Fetal Circulation•Pulmonary bypass

• Lets blood flow skip the lungs• Foramen ovale

•Between atria in interatrial septum•Becomes fossa ovalis in adult

• Ductus arteriosus•Between pulmonary trunk and aorta

• Both pathways close after birth


The Blood Vessels

Fetal Circulation

Figure 13-25(a)

The Blood Vessels

Fetal Circulation

Figure 13-25(b)

Aging and the CV System

Age Related Changes in the Blood•Decreased hematocrit•Vessel blockage by a thrombus

(blood clot)•Pooling in the legs resulting from

faulty valves



Age Related Changes in the Heart•Reduction in maximal cardiac output• Impaired nodal and conduction function•Stiffening of cardiac skeleton•Retricted coronary flow due to

atherosclerosis•Fibrous replacement of damaged

myocardium



Age Related Changes in Blood Vessels•Embrittlement of arterial walls by

arteriosclerosis• Increased risk of aneurism

•Calcium deposits in lumen• Increased risk of thrombus

•Thrombus formation at atherosclerotic

plaques


The Cardiovascular System in Perspective

FIGURE 13-26 Functional Relationships Between the Cardiovascular System and Other Systems

Figure 13-261 of 11Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings


• Stimulation of mast cells produces localized changes in blood flow and capillary permeability

• Delivers immune system cells to injury sites; clotting response seals breaks in skin surface; carries away toxins from sites of infection; provides heat

The Integumentary System


The Skeletal System

• Provides calcium needed for normal cardiac muscle contraction; protects blood cells developing in bone marrow

• Provides calcium and phosphate for bone deposition; delivers EPO to bone marrow, parathyroid hormone, and calcitonin to osteoblasts and osteoclasts


The Muscular System

• Skeletal muscle contractions assist in moving blood through veins; protects superficial blood vessels, especially in neck and limbs

• Delivers oxygen and nutrients, removes carbon dioxide, lactic acid, and heat during skeletal muscle activity


The Nervous System

• Controls patterns of circulation in peripheral tissues; modifies heart rate and regulates blood pressure; releases ADH

• Endothelial cells maintain blood-brain barrier; help generate CSF


The Endocrine System

• Erythropoietin regulates production of RBCs; several hormones elevate blood pressure; epinephrine stimulates cardiac muscle, elevating heart rate and contractile force

• Distributes hormones throughout the body; heart secretes ANP


The Lymphatic System

• Defends against pathogens or toxins in blood; fights infections of cardiovascular organs; returns tissue fluid to circulation

• Distributes WBCs; carries antibodies that attack pathogens; clotting response assists in restricting spread of pathogens; granulocytes and lymphocytes produced in bone marrow


The Respiratory System

• Provides oxygen to cardiovascular organs and removes carbon dioxide

• RBCs transport oxygen and carbon dioxide between lungs and peripheral tissues


The Digestive System

• Provides nutrients to cardiovascular organs; absorbs water and ions essential to maintenance of normal blood volume

• Distributes digestive tract hormones; carries nutrients, water, and ions away from sites of absorption; delivers nutrients and toxins to liver


The Urinary System

• Releases renin to elevate blood pressure and erythropoietin to accelerate red blood cell production

• Delivers blood to capillaries, where filtration occurs; accepts fluids and solutes reabsorbed during urine production


The Reproductive System

• Sex hormones maintain healthy vessels, estrogen slows development of atherosclerosis

• Distributes reproductive hormones; provides nutrients, oxygen, and waste removal for developing fetus; local blood pressure changes responsible for physical changes during sexual arousal

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